冬季寒潮爆发频数与ENSO的联系     

叶更新  王智宇 《吉林气象》2010,(2):2-7

利用通化市（41°41＇N,125°54＇E）单站温度资料和NCEP／NCAR月平均高度场资料,分析了ENSO发生前一年和当年冬季寒潮爆发频数的年际变化以及与之相对应的大气环流分布,结果发现。寒潮发生的频数与ENSO之间的联系存在明显的年代际变化,在上世纪70年代中期以前,EL-nino和LA—nina发生的前一年冬季通化市发生寒潮次数明显偏多,而70年代中期以后,无论是EL-nino还是LA—nina在发生前一年冬季通化市发生寒潮次数明显偏少;而EL-nino发生的当年,在70年代以后,寒潮次数明显偏多;在LA—nina发生的当年,寒潮发生的多少不明显。ENSO发生前一年冬季的大气环流与寒潮发生次数有关。在EL—nino和LA-nina发生前,寒潮多年和少年在北半球大多数地区大气环流距平呈现相反的状态。  相似文献   

热带深对流云对CO、NO、NOx和O3的垂直输送作用   总被引：2，自引：1，他引：1  

银燕  曲平  金莲姬 《大气科学》2010,34(5):925-936

利用2005年11月至2006年2月ACTIVE (Aerosol and Chemical Transport in tropIcal conVEction) 外场试验期间在澳大利亚北部达尔文地区取得的CO、O3、NO和NOx飞机探测资料, 并结合HYSPLIT后向轨迹模式结果, 分析这几种气体成分在对流卷云砧内外的分布情况, 并探讨热带深对流云对于污染气体的垂直输送作用。分析结果显示, 在孤立对流云卷云砧中, 云砧内部O3、NO、NOx浓度均大于云外; 而CO则不同, 只有在近地面浓度高时才如此, 在近地面浓度较小时, 卷云砧内部的浓度反而小于云外。进一步分析造成这两类气体分布差异的原因, 发现CO主要借助深对流云将对流层下层以及对流云周围环境中的CO夹卷并动力垂直输送到对流云顶部卷云砧中, 而对于O3、NO和NOx来说, 除了上述作用以外, 还可能与对流云内部其他物理机制(如闪电), 造成新的O3、NO和NOx有关, 这些新生气体随着风暴内部强烈的上升气流被最终输送进云砧中。  相似文献   

How Well do Existing Indices Measure the Strength of the East Asian Winter Monsoon？   总被引：44，自引：7，他引：37  

WANG Lin  CHEN Wen 《大气科学进展》2010,27(4):855-870

Defining the intensity of the East Asian winter monsoon (EAWM) with a simple index has been a difficult task. This paper elaborates on the meanings of 18 existing EAWM strength indices and classifies them into four categories: low level wind indices, upper zonal wind shear indices, east-west pressure contrast indices, and East Asian trough indices. The temporal/spatial performance and prediction potential of these indices are then analyzed for the 1957--2001 period. It reveals that on the decadal timescale, most indices except the east--west pressure contrast indices can well capture the continuous weakening of the EAWM around 1986. On the interannual timescale, the low level wind indices and East Asian trough indices have the best predictability based on knowledge of the El Nino-Southern Oscillation and Arctic Oscillation, respectively. All the 18 existing indices can well describe the EAWM-related circulation, precipitation, and lower tropospheric air temperature anomalies. However, the variations of surface air temperature over large areas of central China cannot be well captured by most indices, which is possibly related to topographic effects. The results of this study may provide a possible reference for future studies of the EAWM.  相似文献   

The Role of Land–sea Distribution and Orography in the Asian Monsoon. Part I： Land–sea Distribution   总被引：3，自引：3，他引：0  

XU Zhongfeng  QIAN Yongfu  FU Congbin 《大气科学进展》2010,27(2):403-420

A number of AGCM simulations were performed by including various land--sea distributions (LSDs), such as meridional LSDs, zonal LSDs, tropical large-scale LSDs, and subcontinental-scale LSDs, to identify their effects on the Asian monsoon. In seven meridional LSD experiments with the continent/ocean located to the north/south of a certain latitude, the LSDs remain identical except the southern coastline is varied from 40^o to 4^oN in intervals of 5.6^o. In the experiments with the coastline located to the north of 21^oN, no monsoon can be found in the subtropical zone. In contrast, a summer monsoon is simulated when the continent extends to the south of 21^oN. Meanwhile, the earlier onset and stronger intensity of the tropical summer monsoon are simulated with the southward extension of the tropical continent. The effects of zonal LSDs were investigated by including the Pacific and Atlantic Ocean into the model based on the meridional LSD run with the coastline located at 21^oN. The results indicate that the presence of a mid-latitude zonal LSD induces a strong zonal pressure gradient between the continent and ocean, which in turn results in the formation of an East Asian subtropical monsoon. The comparison of simulations with and without the Indian Peninsula and Indo-China Peninsula reveals that the presence of two peninsulas remarkably strengthens the southwesterly winds over South Asia due to the tropical asymmetric heating between the tropical land and sea. The tropical zonal LSD plays a crucial role in the formation of cumulus convection.  相似文献   

Comparisons of Soil Moisture Datasets over the Tibetan Plateau and Application to the Simulation of Asia Summer Monsoon Onset   总被引：1，自引：0，他引：1  

BAO Qing  LIU Yimin  SHI Jiancheng  WU Guoxiong 《大气科学进展》2010,27(2):303-314

The influence of soil moisture on Asian monsoon simulation/prediction was less studied, partly due to a lack of available and reliable soil moisture datasets. In this study, we firstly compare several soil moisture datasets over the Tibetan Plateau, and find that the remote sensing products from the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) can capture realistic temporal variations of soil moisture better than the two reanalyses (NCEP and ECMWF) during the pre-monsoon season...  相似文献   

Definition and Features of the North Edge of the East Asian Summer Monsoon          下载免费PDF全文

TANG Xu  CHEN Baode  LIANG Ping  QIAN Weihong 《Acta Meteorologica Sinica》2010,24(1):43-49

By using daily total precipitable water(TPW) amount from the ECMWF reanalysis(ERA-44a) data in 1958-2001,the north edge of the Asian sub-tropical summer monsoon is defined by a normalized precipitable water index(NPWI),and its climatology and interannual/interdecadal variability are examined.The results show that two monsoon systems(the Indian and East Asian monsoon systems) can be identified in terms of monsoon edge defined by the NPWI over Asia.The mean north edge goes in the west-east direction along ...  相似文献   

涡分辨率全球海洋环流模式LICOM模拟的吕宋海峡流场的季节变化     

李云  俞永强 《气候与环境研究》2014,19(5):547-558

分析了一个1/10°的涡分辨率全球环流模式LICOM(LASG/IAP Climate system Ocean Model)对吕宋海峡附近海洋环流的模拟能力。结果表明,模拟的吕宋海峡附近上层环流及输运具有明显的季节变化特征,除6月是东向净流出外,其余月份均为西向流入,冬季流量最大。年平均流量在-3.76 Sv(1 Sv=106 m3/s),其中上层(600 m以上)流量起主要贡献,为-3.60 Sv,与目前已有的研究结果基本一致。南海通过6个海峡完成与外界的水交换,其中吕宋海峡和巴拉巴克海峡是大洋水进入南海的主要通道,其余海峡均以流出为主,流出量最大的是台湾海峡(1.99 Sv),其次是卡里玛塔海峡(1.03 Sv)。进一步分析表明,由季风引起的埃克曼输送量约占吕宋海峡流量的11%,而由季风引起的吕宋海峡压力梯度形成的西向的地转流对吕宋海峡的输运起支配作用。作为黑潮源头的太平洋北赤道流流量对吕宋海峡输运的季节变化也有一定影响。  相似文献   

基于MJO的延伸预报   总被引：30，自引：3，他引：27  

丁一汇  梁萍 《气象》2010,36(7):111-122

近10年来,2～4周的延伸预报成为天气和气候业务预报发展的一个方向。目前比较有效的方法是根据季节内振荡的传播,尤其是MJO振荡(30～60天周期)的传播来制作延伸期预报。国际上一些天气-气候预报中通过数年的业务试验已取得了初步结果。作者首先介绍了MJO振荡及季风的季节内振荡(MISO)特征,并从季节内振荡与中纬度相互作用的角度讨论了制作延伸预报的理论依据;进一步对延伸预报的可预报性、预报方法及国内外业务应用进展进行了综述,并以江淮梅雨为例探讨了我国延伸预报的可预报性及信号;最后阐述了延伸预报的发展趋势。  相似文献   

祁连山夏季西南气流背景下地形云形成和演化的观测研究   总被引：8，自引：3，他引：5       下载免费PDF全文

陈添宇  郑国光  陈跃  付双喜 《高原气象》2010,29(1):152-163

利用2007年祁连山地形云的观测试验资料,分析了祁连山夏季西南气流背景下地形云的演化过程,得到了祁连山地形云发展和演变的概念模型。(1)祁连山地形云的水汽主要分布在3500～6500m的范围内,对流层中层的西南气流将水汽由南向北输送到祁连山区。(2)祁连山区水汽比较丰沛,凝结高度和自由对流高度均较低,当湿气团抬升到凝结高度以上时对流有效位能很容易释放,形成有利于产生降水的云系。(3)祁连山每个山峰南北侧昼间的谷风会在山峰辐合抬升,众多山峰形成的祁连山群谷风的抬升作用下容易形成沿山脊排列的中β对流云带,在高空西南气流的推动下移到北侧,是造成北侧降水比南侧大的原因之一。  相似文献   

印度半岛热力变化对亚洲季风环流异常的影响   总被引：2，自引：0，他引：2       下载免费PDF全文

晏红明  杨辉  王灵  梁红丽 《高原气象》2010,29(6):1452-1463

海陆热力差异的季节性变化是季风产生的原始驱动力,因此海洋和大陆任何一方的变化必然会影响季风环流出现异常。本文探讨了欧亚大陆高、低层气温、南亚大陆和印度洋之间海陆热力差异的变化特征,发现南亚大陆的印度半岛区域下垫面的季节性增暖出现最早,其增暖从春季就开始出现,比对流层上层增暖偏早约两个月,相应的低层经向海陆温度梯度由冬季型转为夏季型最早的区域出现在80°E附近。进一步分析了印度半岛下垫面热力异常的变化特征及其与季风环流异常的关系,初步揭示了南亚区域高、低层气温变化的相互联系,发现印度半岛下垫面的迅速增温引起了大气的强感热加热,进而影响高、低层季风环流的异常变化。结果表明,春末夏初印度半岛暖下垫面的加热作用有利于亚洲夏季型季风环流建立偏早,同时也有利于亚洲夏季季风环流的加强,而冷下垫面的作用则相反。  相似文献